100 students are interviewed to see which of biology, chemistry or physics they prefer. 39 of the students are girls. 21 of the girls like biology best.
16 of the boys prefer physics.
11 out of the 34 who prefer chemistry are girls.
What percentage of the students prefer biology?
.

43%

Step-by-step explanation:

There are 39 girls. 21 of them like biology. 11 out of 34 who like chemistry are girls.

No. of girls who prefer biology = 21

There are (100-39) boys. 16 of them like physics. (34-11) of them like chemistry.

No. of boys who prefer biology = 100-39-16-34+11

                                                    = 22

Percentage of students who prefer biology = × 100%

                                                                        = × 100%

                                                                        = 43%

x= cost per bracelet

number of bracelets * x + shipping charge = total cost

so

9x+9=72